This invention relates to the field of measuring devices, and more specifically to an extremely compact pressure measuring device.
Pressure measuring devices, such as sphygmomanometers, typically include a pneumatic bulb which inflates a pressure chamber of an attached sleeve that is fitted over a limb (i.e., an arm or leg) of a patient. A diaphragm or bellows assembly, responsive to changes in fluid pressure of the pneumatic bulb and the sleeve pressure chamber is positioned in a gage housing. A pointer of a dial indicator is interconnected to the bellows assembly by a movement mechanism, whereby inflation of the bellows causes corresponding circumferential movement of the pointer.
Typically, the above referred to movement mechanisms are quite intricate and complex, and are akin in terms of their manufacture and precision to Swiss watches. For example, in one such movement mechanism, a pair of diaphragm springs are attached adjacent opposing ends of a spindle. A bottom end of the spindle is placed in contact with the bellows assembly and a twisted bronze band perpendicularly disposed at the top end of the spindle is connected in parallel by a horizontally disposed bent spring part. As the spindle deflects axially in response to the inflation of the bellows, the bent spring part is also caused to deflect, thereby causing the band to twist. The pointer, attached to the bronze band, therefore is caused to rotate in relation to an adjacent dial face.
Devices, such as the foregoing, include numerous moving and relatively complex components, some or each having multiple bearing surfaces. Therefore, such known devices must be manufactured with relatively strict tolerance margins and their associated costs in terms of both precision and failure rate in order to minimize errors.
In addition, any adjustments required after assembly of the above mechanisms, such as to null the pointer or adjust the sensitivity of the device, require substantial tear-down or at least significant and undesired disassembly.
Furthermore, discrete and separate elements are typically required within the instrument housing for independently supporting the movement mechanism and the bellows assembly, respectively, and for defining an expansion chamber for the bellows assembly therebetween.
A more recent and simplified movement mechanism developed by Applicants and described in U.S. Pat. No. 5,996,829, incorporated by reference in its entirety, includes a vertically disposed axial cartridge having a spirally wrapped ribbon spring with one end mounted to an axially movable elongate shaft and the remaining end to a fixed tubular sleeve. A bottom portion of the shaft is positioned relative to an expandable diaphragm or bellows, wherein subsequent axial translation of the shaft, caused by movements of the diaphragm, elongates the spirally wound ribbon spring and produces repeatable circumferential movement of a pointer supported at the top end of the shaft.
Subsequently, and in order to further reduce the overall size and complexity of the above structure while using the same form of movement mechanism, it has been determined that the diaphragm could be conveniently mounted in sealing relation to the bottom facing side of a single supporting plate. This advance, described in U.S. patent application Ser. No. 09/172,552, also incorporated by reference in its entirety, permits the design of a housing retaining the movement mechanism far more compactly. However, even with this improved design, there is still a continuing general need in the field to further optimize and streamline the housing. There is also a co-existing need in the marketplace to reduce the complexity in the manufacture of pressure measuring devices without compromising their reliability.
Furthermore, numerous pressure measuring devices according to the prior art are typically bulky and relatively heavy. As a result, these devices are easily prone to damage when dropped or otherwise mishandled.
A further problem encountered more specifically with blood pressure measuring devices involves the need for both an inflatable cuff or sleeve and a separate housing which is tethered thereto. Often the instrument housing is difficult to read for the patient who takes their own blood pressure readings or for the doctor or caregiver due to glare against the viewing window of the device or the viewing angle. It is therefore another desired need to be able to more effectively adjust the instrument housing in order to permit easier and more accurate readings.
It is a primary object of the present invention to provide a pressure measuring device which overcomes the above deficiencies of the prior art.
It is another primary object of the present invention to provide a housing for a pressure measuring device, such as for measuring blood pressure, which is more compact and less expensive to manufacture than previously known devices while being equally reliable.
It is yet another primary object of the present invention to provide a housing for a lightweight, portable pressure sensitive device which can be effectively coupled to an inflatable sleeve, such as a blood pressure cuff.
It is still a further object to provide a pressure measuring device which is lightweight, less resistant to shock or vibration loads, and which is equally reliable in comparison to known devices which are heavier and bulkier.
It is yet another primary object of the present invention to provide a blood pressure measuring device which is easier to use and more convenient than those which are currently available.
Therefore and according to a preferred aspect of the present invention, there is disclosed a shallow profile pressure sensitive device comprising a compact housing having an interior cavity and a sleeve sized to be fitted about the limb of a patient. The sleeve means receives the housing, which includes an indicator disposed an upper housing portion and a narrow lower housing portion sized to be fitted within the receiving means of the sleeve. The lower portion of the housing includes a ball-shaped male engagement member permitting the housing to be pivotally mounted to the sleeve and further permit angled viewing of the indicator. Certain alternatives are easily imagined. For example, the positions of the male and female engagement members could be reversed; that is, a socket could be provided on the instrument housing with the mating end being provided on the sleeve.
Preferably, the housing retains a pressure responsive element disposed within the interior cavity of the housing, the pressure responsive element including a narrowed portion correspondingly fitted within the narrowed portion of the housing. A movement mechanism interconnects a movable surface of the pressure responsive element with the indicator.
According to a preferred version, the movement mechanism includes an axially displaceable shaft member and a ribbon spring member helically wound an axial portion of the shaft member. The ribbon spring includes opposing ends, one of which is attached to a fixed part of the housing and a remaining end which is attached to the shaft member. As the movable surface of the pressure responsive member is caused to move by incoming fluid entering a sealed chamber of the housing from the sleeve, the axially displaceable shaft member is caused to move both axially and circumferentially, producing corresponding indicator movement. In a preferred version, the pressure responsive element is a diaphragm used in connection with a blood pressure cuff.
The sleeve includes a socket sized to receive the ball-shaped engagement end including a port in fluid communication with the sleeve. The housing is, therefore, attached to and capable of both rotational and pivotal movement relative to the sleeve.
According to another preferred version, the housing includes a peripheral bumper guard which protects same from shock or impact loads. Preferably, the guard is attached to the upper housing portion and extends above a viewing window.
According to yet another preferred version, the viewing window further includes an anti-reflective coating to minimize glare.
According to yet another preferred aspect of the present invention, there is disclosed a blood pressure measuring device comprising a housing having an interior cavity, and an inflatable sleeve for wrapping around a patient limb. Disposed within the interior cavity are an indicator mounted within an upper housing portion, a pressure responsive element having at least one movable surface and a movement mechanism interconnecting the at least one moveable surface and the indicator. The housing includes a narrow lower portion including a ball-shaped engagement end for engaging the sleeve such that the housing is pivotally mounted in relation to the sleeve.
In a preferred embodiment, the downwardly extending portion of the housing can be directly coupled to an inflatable blood pressure cuff. This attachment can take place without the need for hoses. Most preferably, the device housing, having a very shallow profile, protrudes slightly from the exterior of the sleeve and is sealed or otherwise attached thereto. Furthermore, in another preferred variation, the housing can be selectively rotated or pivoted with respect to the inflatable sleeve, allowing either the patient or the caregiver to perform and read the measurement.
In another preferred variation, the housing can be used with an RF-welded blood pressure sleeve such that the housing can be attached directly to the inflatable sleeve. A sealed port provided in the sleeve is sized to receive the ball-shaped engagement end of the compact housing.
The proximity of the diaphragm within the housing interior to incoming fluid and the positioning of the movement mechanism within the attachment cavity of the housing affords significant overall savings in the overall profile of the device and therefore allows the above attachment to be extremely efficient.
Preferably, the viewing window of the device housing includes an anti-reflective coating to minimize glare.
An advantage provided by the present device is that the gauge housing can be coupled directly to a blood pressure sleeve or cuff without any interconnecting hoses, providing a highly compact and efficient design with fewer parts.
Furthermore, the overall compactness of the lightweight housing design permits use in literally any form of measuring device, medical or industrial, having a pressure sensitive element including, but not limited to, valves, gauges, switches, and leak detectors.
Yet another advantage of the present invention is a lightweight pressure sensitive housing as described herein allows improved and simplified manufacturability and versatility, but without compromising reliability.
These and other objects, features, and advantages will become apparent from the following Detailed Description which should be read in conjunction with the accompanying drawings.